1. Field of the Invention
The present invention generally relates to a pump driving unit for driving a pump used for supporting or substituting of cardiac function, such as a blood pump which is applied to an artificial heart or an intra-aortic balloon pump which supports cardiac function. More particularly, this invention provides for miniaturization of the pump driving unit.
2. Description of the Background
A known type of a pump driving unit for driving a pump used for supporting or substitution of cardiac function, such as a blood pump or IABP (Intra-Aortic Balloon Pump) is disclosed in Japanese Patent Laid-Open Publication No.11-188091. This publication discloses an air pressure driven type pump driving unit, which drives a pump used for an artificial heart.
A conventional air pressure driven type pump driving unit such as the above cited publication, generally has a compressor, a high pressure accumulation chamber and a low pressure accumulation chamber, and is placed outside of a human body. The high pressure accumulation chamber is connected to an output port of the compressor and the low pressure accumulation chamber is connected to an intake port of the compressor, respectively. These two accumulation chambers are connected to a connection port of the artificial heart through a selector valve. In response to operation of the selector valve, these accumulation chambers are selectably communicated with the connection port, and pressure fluctuation thereby occurs. The pressure fluctuation which is generated between these pressure accumulation chambers drives a pump used for supporting or substitution of cardiac function.
The conventional air pressure driven type pump driving unit must have a compressor, and high and low pressure accumulation chambers, and so is bulky. To reduce the size of the driving unit, U.S. Pat. No. 5,766,207 suggests placing the compressor in the low pressure accumulation chamber. However, the unit still requires a compressor and a low pressure accumulation chamber, which limits the size reduction of the pump driving unit. Since the pump driving unit must always accompany the user, this limits the user's range of activity.